Sleeve bearings are plain bearings which have very few moving parts in their construction. This article explains their applications and comparison with ball bearings.
Bearings carry load and facilitate motion, hence, they have a wide range of applications. They are usually found in cars, computer fans, washing machines, etc. A ball bearing, which is visible in the wheel of a bicycle, comprises two hardened metal rings, one inside the other, which are separated by a number of spherical metal balls, which in turn are surrounded by lubricants. As these balls are present inside the ball bearings, and they run in the concave grooves which are set into each of the rings.
A sleeve bearing has a single internal rotating cylinder present in a metallic groove or sleeve. It is porous and self-lubricating. Its design has just two moving parts, the outer sleeve and the inner rotating cylinder, unlike ball bearings, which have a number of spherical metal balls lined up on its inside. The outer sleeve can be whole, clenched, or split between two halves.
The most common differences between these two types of bearings are explained below in a tabulated form.
- They are about 1 to 3 decibels quieter as compared to ball bearings.
- In an extremely low temperature environment, they have a longer expected lifetime.
- They are cheaper in cost as compared to ball bearings.
- They require contact on the whole surface of the inner shaft, creating more friction as compared to same size ball bearings.
- In a high temperature environment, their lifespan decreases eventually.
- Their lifespan reduces when they are placed in a non-vertical position.
- They are more tolerant as compared to sleeve bearings in terms of heat and functioning.
- They can be positioned either horizontally or vertically, without any ill-effect.
- Since their inner balls contact each other, they generate very less friction on the inner walls.
- They make a lot of noise, and generate a louder frequency sound.
- They lose efficiency, wear down quickly, and become louder over a period of time.
- They are very expensive as compared to sleeve bearings.
As seen from the table above, ball bearings generate a lot of noise, and this difference is typically noticed while considering the example of ceiling fans. It is also observed that, the noise created by ordinary fan blades usually overcomes the noise of the bearings. Sleeve bearings are much more efficient and less noisier, hence, they are widely used for applications like industrial motors which rotate at high speeds, or high-speed turbo machines.